The four AAA-rated U.S. insurance companies will not be placed on negative outlook, even though the U.S. sovereign outlook has been cut to negative, Fitch Ratings said on Tuesday.

The four are all privately held or are mutual associations: New York Life , Northwestern Mutual , TIAA and USAA.

Fitch said each company had strong liquidity and capital that was independent of government support, and therefore there was no need to lower their outlooks.

Furthermore, in the event of a future U.S. sovereign downgrade, we believe it would be reasonable for the four 'AAA' companies to maintain ratings potentially one to two notches higher than the U.S. government's rating, Fitch said in a statement.

(Reporting by Ben Berkowitz; Editing by Ted Kerr)